System and method for powering accessories in a hybrid vehicle

ABSTRACT

A system and method for providing power to vehicle accessories having operational power requirements in excess of 1 kilowatt. The system is employed in conjunction with a vehicle comprising a main power unit and an electric motor, the main power unit providing more than 42 volts of power to a DC power bus from which the electric motor draws power to propel the vehicle. The system comprises a vibration dampening mounting structure affixed to the vehicle. A vehicle accessory requiring operational power in excess of 1 kilowatt and an electric accessory motor are affixed to the mounting structure. The electric accessory motor is mechanically coupled to the vehicle accessory. The electric accessory motor draws electric power from the DC power bus to provide operational power to the vehicle accessory. The vehicle accessory can be a scroll type air compressor.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.10/160,877, filed May 31, 2002 now U.S. Pat. No. 7,119,454, which ishereby incorporated in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The field of the present invention is generally motor vehicles, and inparticular systems within motor vehicles that power vehicle accessories.

2. Background

In conventional vehicles, i.e., vehicles that are neither hybridvehicles nor electric vehicles, accessories such as hydraulic pumps,water pumps, vacuum pumps, and compressors for air brakes or airconditioning systems are powered directly from the internal combustionengine. The power required by these accessories may be steady overextended periods of time, as in the case of a water pump that is used tohelp cool the engine, or it may be required in short bursts when neededby the accessory, as in the case of hydraulic accessories or air brakes.Because such accessories have relatively high power requirements, themost economical and efficient source of power for these accessories isthe internal combustion engine.

In hybrid vehicles that include an internal combustion engine, either inseries or in parallel with the electric motor, these same accessoriesare often powered from the internal combustion engine in much the sameway as in a conventional vehicle. Alternatively, in some hybrid vehiclesand in most electric vehicles, the traditional accessories are replacedwith a wholly electric version of the accessory to perform the samefunction, such as an electric air conditioning system or an electricallypowered compressed air brake system.

In implementing either of the above solutions to power vehicleaccessories, however, inefficiencies are introduced into a vehicle.These inefficiencies may effect the cost of the vehicle, the performanceof the vehicle, or both. For example, if a hybrid or electric vehicleincludes electric versions of one or more accessories, the inefficiencyintroduced in the hybrid vehicle is in the overall cost of the vehicle.The increased cost arises because the electric version of an accessorymust initially be developed and tested. Additionally, the cost of theelectric version of the accessory will typically remain high over aperiod of one to several years because vehicles which use the electricversion of the accessory do not have the high production quantities ofconventional vehicles.

Conversely, if a hybrid vehicle implements a vehicle accessory in thetraditional manner, i.e., powered directly from an internal combustionengine, the vehicle will experience inefficiencies in fuel economy. Theinefficiencies arise when the internal combustion engine provides powerdirectly to the accessories and the electric motor and/or the batteriesdo not require power. During these periods, the engine necessarilyconsumes fuel to provide the power required by the accessories. Anyexcess power generated by the engine, however, is lost because it cannotbe otherwise used or stored by the vehicle.

SUMMARY OF THE INVENTION

The present invention is directed to a system and method for drivingvehicle accessories having operational power requirements in excess of 1kilowatt. The system and method are used in conjunction with a vehiclecomprising, a main power unit and an electric motor. The main power unitprovides more than 42 volts of power to a DC power bus and the electricmotor draws power from the DC power bus to propel the vehicle. Thesystem for providing power to the vehicle accessories comprises avibration dampening mounting structure and an electric accessory motor.The electric accessory motor is electrically coupled to the DC power busand mechanically coupled to a vehicle accessory to provide operationalpower to the vehicle accessory. The electric accessory motor and thevehicle accessory are affixed to the vibration dampening mountingstructure, and the vibration dampening mounting structure is affixed tothe vehicle. The vibration dampening mounting structure may be affixedto any advantageous location on the vehicle, including inside or outsideof an engine compartment.

The types of vehicle accessories that may be driven using the system ofthe present invention include compressors, such as brake air compressorsor air conditioning compressors, hydraulic pumps, such as those used forpower steering or other heavy duty hydraulic equipment, water pumps, andvacuum pumps. Each of these types of vehicle accessories haveoperational power requirements that exceed 1 kilowatt, and each may beof the same type used in conventional vehicles that are powered byinternal combustion engines.

The method of providing power to the vehicle accessories comprisesmechanically coupling an electric accessory motor to a vehicle accessoryrequiring in excess of 1 kilowatt of operational power. The electricaccessory motor is also electrically coupled to the DC power bus. Theelectric accessory motor and the vehicle accessory are mounted to thevehicle using a vibration dampening means. The electric accessory motordraws power from the DC power bus to drive the vehicle accessory.

Other aspects, advantages, and novel features of the invention, willbecome apparent from the following Detailed Description of PreferredEmbodiments, ‘when considered in conjunction’ with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present inventions taught herein areillustrated by way of example, and not by way of limitation, in thefigures of the accompanying drawings, in which:

FIGS. 1 a-1 c schematically illustrate systems of driving vehicleaccessories according to the prior art;

FIG. 2 schematically illustrates a system of driving vehicle accessoriesin accordance with an embodiment of the present invention;

FIGS. 3 a and 3 b illustrate a mounting structure for two vehicleaccessories, a scroll air compressor and a hydraulic pump, driven by asingle accessory motor;

FIG. 4 schematically illustrates a system of driving vehicle accessoriesin accordance with another embodiment of the present invention;

FIG. 5 is a perspective view of a mounting structure for two vehicleaccessories, a scroll air compressor and a hydraulic pump, driven byseparate accessory motors;

FIG. 6 is an exploded view of a gear assembly used to couple a vehicleaccessory to an accessory motor; and

FIG. 7 schematically illustrates ‘a system of driving vehicleaccessories in a refuse collection truck in accordance with anotherembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning in detail to the drawings, FIGS. 1 a-1 c illustrate systems ofdriving vehicle accessories as practiced in the prior art. FIG. 1 aschematically illustrates a conventional vehicle 9 (e.g., a passengercar, a light truck, a heavy duty vehicle such as a refuse collection‘truck or transit bus, or other type of vehicle) having an internalcombustion engine 10. The internal combustion engine has two outputshafts 12, 14. The first output shaft 12 is coupled to an input shaft 41of a transmission 40 that may be used to propel the vehicle using adrive shaft 42. Alternatively, the power provided to the transmission 40may be directed into a transfer case 45 and used to drive a powertake-off shaft 46. The power take-off shaft 46 may be used, for example,to drive an additional axle in a four-wheel drive vehicle or to drive ahydraulic pump used in conjunction with heavy duty equipment such as thelift mechanism in a dump truck or a compactor in a refuse collectiontruck.

The second output shaft 14 of the internal combustion engine drivesaccessories 20, 30 using a belt drive assembly. The belt drive assemblycomprises a first pulley 15, affixed to the output shaft 14 of theinternal combustion engine, a belt 16 that connects the first pulley 15to two receiving pulleys 22, 32 that are in turn affixed to input shafts21, 31 of accessories 20, 30, respectively. Additional receiving pulleysand accessories may also be included. The accessories 20, 30 in aconventional vehicle often include, for example, a compressor for an airconditioner or air brakes, a water pump, an alternator to recharge thestarting battery and provide accessory power, or a hydraulic pump forpower steering.

FIG. 1 b schematically illustrates a hybrid vehicle 50 having a paralleldrive system as practiced in the prior art. The parallel hybrid vehicle50 includes an internal combustion engine 10 to drive the accessories20, 30 in the same manner as the conventional vehicle 9 of FIG. 1 a. Theoutput shaft 12 of the internal combustion engine 10 is coupled to aninput shaft 52 of a mechanical coupling 54. The mechanical coupling 54is also coupled to an electric motor 53 with an integrated generator.The electric motor may power the drive shaft 51 using power provided bya battery 60 through an inverter 62 or, alternatively, the internalcombustion engine 10 may power the drive shaft 51 through the mechanicalcoupling 54. When the internal combustion engine 10 powers the driveshaft 51, the generator integrated into the electric motor 50 may beused to store power in the battery 60.

FIG. 1 c schematically illustrates a hybrid vehicle 69 having a seriesdrive system as practiced in the prior art. The series hybrid vehicle 69includes an internal combustion engine 10 to drive the accessories 20,30 in the same manner as the conventional vehicle 9 of FIG. 1 a. Theoutput shaft 12 of the internal combustion engine 10 is coupled to aninput shaft 71 of a generator 70. When driven by the internal combustionengine 10, the generator 70 provides electrical power to a battery 60and an inverter 62. The battery may provide electrical power to theinverter 62 when the generator 70 is not operating. The inverter 62 iselectrically coupled to an electric motor 80 that propels the vehicle 69via a drive shaft 81.

FIG. 2 schematically illustrates an embodiment of a system 100configured to power vehicle accessories 142, 144, in accordance with thesystems and methods disclosed herein. System 100 is preferablyincorporated into a series hybrid vehicle 100, but system 100 can beincorporated into other types of vehicles. The system 100 has a mainpower unit 102 with at least one power generating source that providesmore than 42 volts of power to a high voltage DC power bus 112. Thepower generating source can comprise an internal combustion engine 104coupled to a generator 108 through a drive shaft 106, a fuel cell 110, amicro-turbine (not shown) or any other appropriate power source.

One or more batteries 114 are electrically coupled to the DC power bus112 to store power generated by the main power unit 102. A firstinverter 116 is electrically coupled to the DC power bus 112 to provideAC power to the electric motor 118 that propels the hybrid vehicle usinga drive shaft 120. Preferably a DC converter 122 is included in system100 to step the high voltage of the DC power bus 112 down to anappropriate level required by low voltage accessories that may beincluded in the hybrid vehicle. For example DC to DC Connector 122 canbe configured to provide 12, 24, or 42 volts to various low voltageaccessories.

A second inverter 124 is coupled to the DC power bus 112 to provide ACpower to an electric accessory motor 126. The output shaft 128 of theelectric accessory motor 126 drives the vehicle accessories 142, 144using a belt drive assembly 148. The electric accessory motor 126provides a total power output that exceeds the operational powerrequirements of any vehicle accessories 142, 144, and preferably theelectric accessory motor 126 is capable of providing a total poweroutput that exceeds the combined maximum power ratings of the vehicleaccessories 142, 144. The belt drive assembly 148 comprises a firstpulley 130, affixed to the output shaft 128 of the electric accessorymotor 126, a belt 132 that connects the first pulley 130 to tworeceiving pulleys 134, 136, each receiving pulley 134, 136 being affixedto an input shaft 138, 140 of one of the accessories 142, 144.Additional receiving pulleys and accessories may also be included. Theelectrical rating of accessory motor 126 is preferably based upon theoperational power requirements of the accessories affixed to the beltdrive assembly 148.

Examples of vehicle accessories that may be advantageously powered bythe electric accessory motor 126 include air compressors, water pumps,hydraulic pumps, vacuum pumps, or other accessories that haveoperational power requirements in excess of 1 kilowatt. In the case ofan air compressor, a piston-type air compressor can be used, or morepreferably, a scroll-type air compressor can be used. Such accessoriesare traditionally powered directly from the internal combustion enginein a conventional vehicle because of their relatively high powerrequirements.

An advantage to using electric accessory motor 126 is that the internalcombustion engine 104 can be shut down when the vehicle and itsaccessories 142 and 144 are adequately powered by the batteries. Thus,with the high power accessories 142 and 144 being driven by theaccessory motor 126, the internal combustion engine 104 may be operatedless frequently than if the accessories 142 and 144 are driven directlyfrom the internal combustion engine 104 which results in greater fuelefficiency. Additionally, because each of these high power accessories142 and 144 may be of the same shaft driven type typically used inconventional vehicles, significant savings may be realized in theoverall cost of the vehicle. These cost savings arise through economiesof scale that are already in place for the shaft driven version of thehigh power accessories 142 and 144, as compared to the development andmanufacturing infrastructure that exists for entirely electronicversions of these same accessories.

An additional advantage of driving the high power accessories 142 and144 with a separate accessory motor 126 is that the accessories 142 and144 can be affixed to any location on the vehicle. The aforementionedhigh power accessories are often mounted within the engine compartmentin a conventional vehicle. Thus, not only do the accessories 142 and 144share the same compartmental space with the engine, but they also sharethe same dirt, dust, high temperature, and vibrations present within theengine compartment, most of which is created by the internal combustionengine. By powering the vehicle accessories 142 and 144 with a separateaccessory motor 126, the vehicle accessories 142 and 144 can be mountedanywhere on or in the vehicle, thus making the accessories 142 and 144more accessible and removing them from an environment that contributesto wear and tear.

FIG. 3 a illustrates an accessory motor 150 coupled to a scroll-type aircompressor 152 and a hydraulic pump 154, all of which are affixed to avibration dampening mounting structure 156. The shaft (not shown) of theaccessory motor 150 is accessible from two opposite sides of theaccessory motor. On one side, the accessory motor 150 is mechanicallycoupled to the air compressor 152 using a clutch 158, which can be ofany appropriate type, pulley 160, and belt mechanism 161. With this typeof coupling, the air compressor 152 may be driven at any time simply byengaging the clutch 158. On the opposite side, the mechanical couplingbetween the accessory motor 150 and the hydraulic pump 154 is a directshaft connection. Thus, when the accessory motor 150 is operative,operational power is provided to the hydraulic pump 154. The type ofmechanical coupling is chosen to best serve the needs of the vehiclewith which the accessories are used. Therefore, many alternative typesof mechanical couplings can be employed.

The vibration dampening mounting structure 156 of FIG. 3 a comprises aplate 162 and mounting bolts 164 to affix the plate to the vehicle inthe manner shown in FIG. 3 b. The mounting bolts 164 are vibrationallyisolated from the mounting plate 162 by interposing a vibrationdampening material 166, such as rubber, between the mounting bolts 164and the mounting plate 162. Additionally, each bolt extends through ahole 168 in the mounting plate 162, without having physical contact withthe mounting plate, and is affixed to supporting structure 170 of thevehicle. Thus, vibrations that would otherwise travel between thevehicle and the accessories are largely absorbed by the vibrationdampening material. Other vibration isolation and dampening techniquescan also be employed.

An advantage of having the accessory motor 150 and the accessories 152and 154 affixed to the vibration dampening mounting structure 156 isthat the vibration dampening mounting structure can be affixed to thevehicle either within the engine compartment or external to the enginecompartment. Additionally, the vibration dampening mounting structure156 may be mounted at any desired orientation relative to the vehiclebecause no overly restrictive mechanical connections (i.e., a driveshaft connection) are required. Regardless of where and how thevibration dampening mounting structure 156 is mounted, the electricalcoupling between the electric accessory motor 150 and the DC power bus,e.g., bus 112, is easily accomplished using insulated wires. Otherconnections required by certain accessories, such as a compressed air orpressurized fluid line, are also easily made regardless of where on thevehicle the accessories are affixed.

FIG. 4 schematically illustrates an alternative embodiment of a system200 configured to power vehicle accessories 210, 230, and 250.Preferably, system 200 is incorporated into a series hybrid vehicle.System 200 includes a main power unit 102 that powers a high voltage DCpower bus 112. In this example, however, each vehicle accessory 210,230, and 250 is driven by a separate accessory motor 212, 232, and, 252,respectively. Each motor 212, 232, and 252 draws power from the DC powerbus 112. For the first accessory 210, the AC motor 212 is preferablyintegrated with an inverter 214 and electrically coupled, through theinverter 214, to the DC power bus 112. The AC motor 212 also preferablyincludes an output shaft 216 that is connected to an input shaft 220 ofthe accessory 210 through a mechanical coupler 218. The mechanicalcoupler 218 can comprise a pulley and belt mechanism, a shaft-to-shaftcoupler, a clutch, or any other type of appropriate mechanical coupler.The mechanical coupler 218 and the AC motor 212 for the first accessory210 are also preferably chosen to suit the power and usage requirementsof the first accessory 210.

In the example illustrated in FIG. 4, the second accessory 230 is drivenin the same manner as the first accessory 210. An AC motor 232 with anintegrated inverter 234 is electrically coupled to the DC power bus 112.The output shaft 236 of the AC motor 232 drives an input shaft 240 ofthe second accessory 230 through a mechanical coupler 238. Themechanical coupler 238 and the AC motor 232 for the second accessory 230are chosen to suit the power and usage requirements of the secondaccessory 230. Thus, the AC motor 232 driving the second accessory 230may have a different power rating than the AC motor 212 driving thefirst accessory 210.

The third accessory shown in FIG. 4 is a hydraulic pump 250 for heavyduty hydraulic equipment, for example, such as a refuse compactor or alift mechanism. An inverter is preferably electrically coupled to the DCpower bus 112 and to an AC motor 252 to provide power to the AC motor252. The output shaft 256 of the AC motor 252 preferably drives theinput shaft 260 of the hydraulic pump 250 through a mechanical coupler258. The mechanical coupler 258 and the AC motor 252 for the hydraulicpump 250 are preferably chosen to suit the power and usage requirementsof the hydraulic pump 250. Additional AC motors may be coupled to the DCpower bus to drive additional accessories as needed.

FIG. 5 illustrates a multi-accessory motor implementation comprisingfirst and second accessory motors 270 and 272 coupled to a scroll-typeair compressor 274 and a hydraulic pump 276, respectively. Both motors270 and 272, as well as compressor 274 and pump 276, are affixed to avibration dampening mounting structure 278. The first accessory motor270 is mechanically coupled to the air compressor 274 using a gearassembly 280. The gear assembly 280 is illustrated in FIG. 6. The gearassembly 280 comprises first and second gears 282, 284, a sleeve 286,and a counter-mass 288. Counter-mass 288 is specifically configured tobe used with the sleeves 286 and gears 282, 284. Thus, counter-mass 288preferably replaces a standard counter-mass that is normally used with ascroll air compressor. The first gear 282 is affixed to the output shaftof the accessory motor, and the second gear 284 is affixed to the inputshaft of the scroll air compressor 274.

The sleeve 286 is preferably made out of a flexible material such asneoprene. A first side 286 a of the sleeve 286 is preferably formed tomate with the teeth of the first gear 282 and the second side 286 b ofthe sleeve 286 is preferably formed to mate with the teeth of the secondgear 284. The teeth of each gear preferably have a depth of at least 3.0mm, and even more preferably of at least 5.0 mm. The sleeve 286 ispreferably manufactured to have a slightly smaller diameter than eachgear 282, 284, requiring the material to be slightly stretched whencoupled to the gears. As such, the sleeve 286 will fit snugly about thegears 282, 284 to provide a coupling that will not slip under mostnormal operating conditions. When assembled, a gap is preferably leftwithin the sleeve 286 between the opposing ends of the first and secondgears 282, 284. Thus, the flexibility of the sleeve 286 and the gearspacing within the sleeve 286 compensate for shaft misalignments thatmay occur during normal operation.

Returning to FIG. 5, the second accessory motor 272 is mechanicallycoupled to the hydraulic pump 276 using a direct shaft-to-shaftconnector 290. The accessory motors 270, 272, the hydraulic pump 276,and the air compressor 274 are affixed to a frame 292. The frame 292 isaffixed to the vehicle using vibration isolation techniques.

FIG. 7 schematically illustrates an embodiment of system 300 configuredto supply power to accessories within a refuse collection vehicle. Theaccessories comprise a scroll air compressor 326, a power steering pump328, and a hydraulic pump 354. In this example, compressor 326 and pump328 are both driven by electric accessory motor 324, while hydraulicpump 354 is driven by electric accessory motor 346. The vehiclecomprises a compressed natural gas engine 302, such as thosemanufactured by John Deere of Moline, Ill., having an output shaft 304that is coupled to a generator 306. The generator 306 generates power ona high voltage DC power bus 308. In the example illustrated in FIG. 3, abattery 310, a power converter 320, and a plurality of power inverters312, 322, 344 are coupled to and receive power from the DC power bus308. The power converter 320 converts the high voltage DC power to lowvoltage DC power for use by low voltage accessories as explained withregard to converter 122. Power inverter 312 converts the high voltage DCpower to AC power for use by an electric motor 316 that propels thevehicle through a drive shaft 318.

Power inverter 322 converts the high voltage DC power to approximately115 volt AC power. This second power inverter 322 powers a constantspeed AC permanent magnet motor 324 and also provides 115 volt AC powerto those vehicle accessories that require such. In this example, the ACmotor 324 drives an output shaft 330 that is coupled to a pulley 332. Abelt couples the pulley 332 to two receiving pulleys 336 and 338 thatare coupled to the input shafts 340 and 342 of the scroll air compressor326 and the power steering pump 328, respectively. The scroll aircompressor 326 provides compressed air for the braking system of thevehicle and the power steering pump 328 provides pressurized hydraulicfluid for the power steering system.

Power inverter 344 converts the high voltage DC power for use by an ACelectric motor 346. The output shaft 348 of the AC motor 346 ispreferably coupled to an input shaft 352 of a hydraulic pump 354 througha mechanical coupler 350. The hydraulic pump 354 can be a heavy dutypump that provides, for example, the necessary fluid pressurization tooperate the lift arms and compactor of the refuse collection vehicle300. The AC motor 346 and power inverter 344 are thus selectedappropriately based upon the power requirements of the hydraulic pump354.

The scroll air compressor 326, the power steering pump 328, and theassociated AC motor 324 can be mounted to a common vibration dampeningmounting structure (not shown) and can be advantageously affixed to anyappropriate part of the vehicle. The hydraulic pump 354 and itsassociated AC motor 346 are preferably mounted on another vibrationdampening mounting structure (not shown) and can also be advantageouslyaffixed to any appropriate part of the vehicle. Factors that may beconsidered in determining where to affix the two vibration dampeningmounting structures include, for example, isolation from undesirableenvironments, ease of access in the event repairs become necessary, andconvenience based upon the function of each accessory, among others.

Thus, as mentioned, an advantage to the systems and methods disclosedherein is that the electric accessory motors can be powered from battery114. If the main power unit 102 comprises an internal combustion engine,then inefficiencies in fuel economy can be reduced, because the internalcombustion engine does not need to supply power to accessories 142 and144 when they do not require power. Additionally, because the systemsand methods described herein can be implemented with conventionalvehicle accessories, cost inefficiencies in hybrid and electric vehiclesmay be overcome. Accordingly, the systems and methods described hereinare not limited to any particular type of vehicle. Rather, the systemsand methods described herein can be implemented in any type of vehicle.

While embodiments and implementations of the invention have been shownand described, it should be apparent that many more embodiments andimplementations are within the scope of the invention. Accordingly, theinvention is not to be restricted, except in light of the claims andtheir equivalents.

1. A vehicle accessory assembly, comprising: a vehicle accessorycomprising an input shaft with a first axis of rotation; an electricaccessory motor comprising an output shaft with a second axis ofrotation that approximately coincides with the first axis of rotation,the electric accessory motor configured to supply power to the vehicleaccessory; a mechanical coupling configured to couple the electricaccessory motor with the vehicle accessory, the mechanical couplingcomprising a first gear affixed to the output shaft of the electricaccessory motor, a second gear affixed to the input shaft of the vehicleaccessory, and a sleeve that mechanically couples the first gear withthe second gear; and, a counter balance configured to operate with thefirst and second gears and the sleeve.
 2. The vehicle accessory assemblyof claim 1, wherein the first and second gears comprise teeth, andwherein the sleeve comprises a first inner portion configured to matewith the teeth of the first gear, and a second inner portion configuredto mate with the teeth of the second gear.
 3. The vehicle accessoryassembly of claim 2, wherein the teeth of the first and second gearscomprise a depth of at least 3.0 mm.
 4. The vehicle accessory assemblyof claim 2, wherein the teeth of the first and second gears comprise adepth of at least 5.0 mm.
 5. The vehicle accessory assembly of claim 2,wherein the sleeve comprises a diameter that is slightly smaller thanthe diameter of both the first and second gears.
 6. The vehicleaccessory assembly of claim 1, wherein the sleeve comprises a flexiblematerial.
 7. The vehicle accessory assembly of claim 1, wherein thefirst and second gears and the sleeve are configured such that there isa gap between the opposing ends of the first and second gears when thefirst and second gears are coupled together by the sleeve.
 8. Thevehicle accessory assembly of claim 1, wherein the vehicle accessory isa scroll air compressor.
 9. The vehicle accessory assembly of claim 1,wherein the vehicle accessory is one of a compressor, a hydraulic pump,a water pump, and a vacuum pump.